As those of ordinary skill in the art will appreciate, punching machines may be employed to punch holes or other cut-outs from a workpiece (e.g., a metal sheet). Typically, punching machines include a tool bearing for a punching tool and a rotary/lifting drive, which moves the tool bearing back and forth along a lifting axis to a working area of the punching machine. Also, the tool bearing is rotatably adjustable about the lifting axis. The punching machine may also include a motor-driven spindle transmission provided with a drive control system. Typically, a rotary/lifting drive having two electric drive motors is provided for the tool bearing of a punching machine. Both drive motors may be arranged laterally next to a drive spindle, which in turn runs in the direction of a lifting axis of the tool bearing. One of the drive motors serves for workpiece punching and for that purpose is connected via a belt drive to a lifting spindle nut disposed on the drive spindle. By driving this spindle transmission in one direction of rotation, the tool bearing (and hence the attached punching tool) is moved with working strokes towards the workpiece to be processed and then by reversing the motor, the tool bearing is moved in the opposite direction. The second drive motor in a conventional punching machine is intended for rotary adjustment of the tool bearing and the punching tool. This drive motor is connected via another belt drive to enable rotation of the punching tool relative to the lifting axis.
Moreover, with a non-uniform force distribution to the two drive units, as would happen, for example, with force introduction at one end of a common drive spindle of two drive units, the drive units would have to accommodate different loads. A uniform construction of the drive units would then be possible only if considerable disadvantages were accepted. For instance, with a uniform construction of the drive units but significantly nonuniform load distribution there would be, for example, a markedly different wear behavior of the two drive units. The service life of the more heavily loaded drive unit would fall considerably behind the service life of the less heavily loaded drive unit. The running properties of the two drive units would also be different from each other. For instance, greater component deformation would occur on the more heavily loaded drive unit than on the less heavily loaded drive unit, the result being that in turn the uniformity of the rotary movements at both drive units would become impaired.
A more efficient punching tool would be desirable.